Spherical bearing and method of making the same

ABSTRACT

A SPHERICAL BEARING IS DESCRIBED WHEREIN A BALL MEMBER IS RETAINED AND SUPPORTED BY A HARDENED SPHERICAL SEAT, THE LATTER BEING DEFINED BY AN INSERT BUSHING THAT IS INTEGRATED INOT A SOCKET STRUCTURE. THE BUSHING WITH A TRUNCATED BEARING BALL NESTED BY THE INNER BUSHING SURFACE IS FUSION WELDED AROUND THE OUTER PERIPHERY OF THE BUSHING TO A HOUSING TO FORM AN INTEGRAL LOAD-CARRYING PART THEREOF. THE FUSION WELD ALSO EXTENDS A SUBSTANTIAL AXIAL DISTANCE OR DEPTH AND IS PREFERABLY MADE WITH AN ENERGIZED BEAM SUCH AS A BEAM OF ELEC-   TRONS. IN THE FORMATION OF A SPHERICAL BEARING FOR A ROD END, A PAIR OF ANNULAR BUSHINGS IS FORMED WITH EACH BUSHING WELDED TO THE ROD END HOUSING TO FORM AN INTEGRAL LOAD-CARRYING PART OF THE ROD END.

01:12. 9, 1913 POTTER ETAL Re. 27,778

SPHERICAL BEARING AND METHOD OF MAKING THE SAME INVE Tons 014 511 LB77276 /cW P0 (1 f BY 4 410 S7620 United States Patent Office Re. 27,778Reissued Oct. 9, 19-73 27,778 SPHERICAL BEARING AND METHOD OF MAKING THESAME Howell L. Potter, New Britain, Richard J. Matt, West Simshury, andRonald E. Refielli, Cromwell, Conn., assignors to Textron, Inc.,Providence, RJ.

Original No. 3,583,775, dated June 8, 1971, Ser. No. 738,515, June 20,1968. Application for reissue June 30, 1972, Ser. No. 268,192

Int. Cl. B2ld 53/10; F16c 1/06 US. Cl. 308-72 Claims Matter enclosed inheavy brackets II] appears in the original patent but forms no part ofthis reissue specification; matter printed in italics indicates theadditions made by reissue.

ABSTRACT OF THE DISCLOSURE A spherical bearing is described wherein aball member is retained and supported by a hardened spherical seat, thelatter being defined by an insert bushing that is integrated into asocket structure.

The bushing with a truncated bearing ball nested by the inner bushingsurface is fusion Welded around the outer periphery of the bushing to ahousing to form an integral load-carrying part thereof. The fusion weldalso extends a substantial axial distance or depth and is preferablymade with an energized beam such as a beam of electrons. In theformation of a spherical bearing for a rod end, a pair of annularbushings is formed with each bushing welded to the rod end housing toform an integral load-carrying part of the rod end.

This invention relates to a spherical bearing assembly and particularlyto a self-aligning spherical bearing assembly and method of assemblingthe same wherein the outer race member comprises a hardened material.

Spherical bearing assemblies comprise a number of different types whichare assembled by a number of different methods. One method, calledswaging, has the outer race of the bearing formed of a material having alow yield point which is then press formed around a hardened steel ball.A difliculty with this type of bearing assembly and method of assemblingthe same is that the choice of material of the bearing member isrestricted since the inner bearing member must be hard enough to serveas a die while the outer race must be soft enough to form. With thismethod of assembly it is not possible to use balls of softer materialssuch as porous lubricant-impregnated balls, or very hard outer racemembers which cannot tolerate the working needed to form the outer racearound the ball.

Another known method for making a spherical hearing involves forming theouter race member of two annular rings which nest the ball between them,the rings being retained in a housing. The annular members are held tothe housing by a press fit within a recess provided therefore in thehousing, or by swaged deformation of the housing to retain the annularinserts. Such bearings again suffer from the disadvantage that the outerrace member is formed of a formable material; they preclude the use of athoroughly hardened housing and outer race surface. Furthermore, thereliance upon a press members reduces the capability of the bearing toabsorb loads parallel to the ring axis and the ball is likely to pop outof the bearing.

Still another bearing construction involves shaping the ball byproviding thereon oppositely disposed cylindrical sections whichseparate oppositely disposed spherical portions. The ball is insertededgewise into a raceway and turned therein to obtain axial retention ofthe bearing. The ball is extensively deformed to enable its placement inthe annular raceway. As a result, a significant amount of axialload-bearing capability is lost.

It is therefore an object of this invention to provide a sphericalbearing structure wherein maximum load-bearing capability is achievedwith minimum physical dimensions.

It is a further object of this invention to provide a high temperaturespherical bearing structure wherein race surfaces of substantiallyelevated hardness are provided.

It is still further an object of this invention to provide ahigh-load-carrying spherical bearing of lightweight construction.

These objects are accomplished by object of as hereafter described inconjunction with the drawings wherein:

FIG. 1 is a front view of a rod end made according to the invention;

FIG. 2 is an exploded view of the rod end of FIG. 1 prior to assembly,parts being broken and shown in section in the plane 2-2 of FIG. 1;

FIG. 3 is a side view of the assembled rod end, partly broken away andin section in the plane 2-2 of FIG. 1;

FIG. 4 is a view similar of FIG. 2 to show a modification:

FIG. 5 is a view similar to FIG. 3 to show the assembled modification ofFIG. 4; and

FIG. 6 is an enlarged longitudinal sectional view of a portion of a rodend according to a further modification.

Briefly stated our invention contemplates forming a spherical bearing ina housing wherein a spherical raceway is divided is not at least twoportions, one of which is formed at the inner surface of an annularbushing which nests a ball upon assembly in the housing and is fusionwelded to the housing.

In FIG. 1, a rod end is shown with a socket housing 10 at one end, andwith a threaded shank 12 at the other end, for connecting to anassociated operating part, not shown. The socket housing is generallyannularly shaped. Within the housing 10 is a bore into which is inserteda pair of annular bushings 141'6, only one of which, 14, is visible inthe view of FIG. 1. A truncated ball 18 is nested between the bushings14-l6 as is shown in FIG. 3. An annular fused zone 20 is formed at theperiphery of the bushing 14 and along the annular seam formed betweenthe bushing 14 and the wall of the bore. The inner surfaces of theannular bushings l4-16 are shaped and sized to form, when coaxiallyplaced adjacent one another a truncated spherically shaped bearing ballseat.

In the formation of the spherical bearing of FIG. 1, the housing 10 isformed of a material preferably selected for its fine grain and highstrength to permit it to carry a major portion of the load. The grainsize of the socket housing 10 is preferably selected to be about ASTM 5or smaller to avoid cracking near the weld zone in the heat-affectedregion. A bore 11 formed therein is preferably concentrically locatedwithin the housing and may be formed by a simple drill operation. Thebore 11 is thus straight cylindrical.

The bushings 14-16 in FIG. 2 are preferably alike and are formed of amaterial, such as stainless steel, selected for its high wearresistance. The inner surfaces 2244 of the bushings are so formed as toprovide, when assembled, half mating portions of a truncated sphericalraceway. The radius of curvature of the raceway portions 22-24 isselected to provide a tight fit with the ball 18 upon assembly in thebore 11. The outer surfaces of the bushings are straight-cylindrical andsized to form a tight annular seam with slight interference with theinner annular wall of the bore 11; in the case of l-inch diameter bore11, this interference is in the order of about 0.0001 inch.

After formation of the insert rings, they are final hardened to about Rc30-36 by a suitable heat-treating process such as placement within anoven kept at hardening temperatures; alternatively, wheresurface-hardening techniques are used, essentially only the sphericalraceway surface is hardened, for instance by induction heat treatmentand quenching.

The ball 18 is formed with a central 26 for mounting to a pin, stud orthe like, not shown. The ball is made of hardenable material and ishardened, say, to Re 53-58, before assembly.

To assemble the bearing, the annular bushings 14-16 are pressembled witha slight press fit in the bore 11 with the ball 18 nested between them.Care must be taken that the walls of the seam are free of contaminationand have a low RMS finish. The bushings may be tack welded into place toavoid distortions during the subsequent seam weldmg.

An energized beam of charged particles such as a beam of electrons 28 isaxially directed at the seam 30, i.e., at the fit of insert 14 in bore11. The beam 28 is so focused at the seam 30 that adjacent sides thereofmay be fused. The power of the beam is adjusted to fuse the adjacentwalls to a depth which is preferably selected to extend over asubstantial portion of the axial width of a bushing. As shown in FIG. 3,the fused zone or cast metal portion 20 extends to about 80 percent ofthe thickness or width of the bushing 14. The annular weld is formed byeither defleeting the beam or rotating the housing 10, and the beampower is adjusted in consideration of the welding speed to assure thatthe weld extends to the desired depth. Upon completion of the welding ofthe bushing 14 to the housing and after cooling of the assembly, thebeam is directed at the opposite axial side 30 of the seam, i.e. betweenbushing 16 and bore 11, to establish an annular weld zone 32 similar tozone 20.

Upon completion of the welding operation, the original tight fit of theball 18 with the spherical raceway is automatically relieved byshrinking action inherent in the cooling of the cast metal, to provide afreely movable bearing ball. The conventional additional step of freeingthe ball has been eliminated. Beam focus and power are controlled toselect the width of the fusion zone and thus the amount of shrinkage tofree the ball. Moreover, by limiting beam penetration to theapproximately 80 percent figure noted, the concentric positioning actionof the interference fit of bushings 14-16 in bore 11 is never lost; itremains to assure a central zone of radial-load support, unaffected bythe welds.

Although an electron beam can be adjusted to Weld the entire axial seam30-30 in one annular sweep, the preferred and more controllableoperation is performed in the two-welding step as described above,leaving a central zone unaffected by welding.

The beam may be slightly radially offset relative to the seam to favorfusing the bushing and reducing the fusion of housing material. It willbe understood that slight variations in this radial offset willestablish the degree of freeup" or clearance upon weld cooling.

FIG. 4 illustrates a more generally spherical bearing assembly. In thisfigure, an annular housing 34 is provided with a counter bore 36 and atruncated spherically shaped inner seat 38. The spherically shaped wall38 may be facehardened by flame hardening or by the addition of a hardcoating thereon. The housing 34 generally is made of a material having ahigh strength characteristic.

An annular bushing 40 is formed having an outer diameter selected toform a tight seam when assembled in the counter-bore 36 and is providedat the inner surface with a truncated spherically shaped raceway 42. Theinner surfaces 38-42 form a similar truncated unitary spherical racewayas the inner surfaces 22-24 of the bushings 14- 16. The bushing 40 maybe hardened prior to assembly within the counterbore 36.

A hardened bearing ball 44 is formed or selected with a diameter tosnugly fit within the truncated spherical raceway formed by the bushinginner surface 42 and the housing surface 38. The FIG. 5 illustrates theassembly with the ball nested between the housing 34 and the bushing 40.

After the preassembly of the bearing elements as shown in FIG. 5 a beamof electrons 28 is directed at the seam 46 formed between the bushingand the inner wall of the counter-bore 36. The focus and power of thebeam are adjusted to fuse and weld the bushing 40 to the housing 34.Preferably the axial depth of the weld zone 50 extends throughout theaxial width of the bushing 40. Upon completion of the annular weld, theball 44 is free to move within the truncated spherical raceway.

The spherical bearing of this invention may be advantageously providedwith a raceway liner exhibiting a desired characteristic and which maybe generally nondeformable. FIG. 6 illustrates a rod end bearingprovided with such liner. Each of the annular bushings 14-16 has itsinner truncated spherical raceway face-hardened with a liner 52-52.These liners may be provided by addition of a heat-resistant hardenedbrittle material such as obtained by the flame spraying of tungstencarbide. Where a slippery low friction surface is desired, a dry filmmay be employed such as a liner composed of tetrafiuoroethylene ornylon. The liners are applied after the formation of the bushings 14-16and the liner thicknesses are taken into account in determining thediameter of the truncated spherical raceways of the bushings. Damage tothe liners is entirely avoided during assembly since the high-speedelectron beam welding avoids excessive heat buildup and eliminates theprior art cold swaging step.

Other high temperature dry film lubricants, and/or corrosionandabrasion-resistant coats can be applied to the race surfaces. Aluminumoxide, chrome carbide films and the like are possible with the bearingconstruction of my invention.

The electron-beam-welded construction permits the use of any desiredrace finish, whether machined, ground or polished, and further permitsaccurate control of race geometry with or without lubricating grooves. Asmoothly finished race increases the actual load-carrying contact area,reduces wear and the tendency to score and gall. The welding of theinserts to the housing results in an increase of the load-carryingcapacity of the bearing for a given weight, since the insert becomes anintegral part of the load-carrying part of the housing.

Having thus described our invention, we claim:

A self-aligning spherical bearing assembly comprising a metallicload-carrying housing having a bore,

a bearing ball,

an annular metallic bushing mounted within the bore and provided at theinner surface thereof about an axis with a truncated spherically shapedraceway sized to snugly nest the ball,

said bushing having a substantial axial portion of its peripheral sidefused to the wall of the bore to form an integral load-carrying part ofthe housing] [2. A bearing assembly according to claim 1, wherein atleast the raceway portion of said bushing is relatively hard andnon-ductile] [3. A self-aligning spherical bearing assembly a truncatedbearing ball having a continuous hardened running surface,

a metallic rod end housing having a bore,

a pair of like metallic bushings each having at its inner surface a halfportion of a truncated spherically shaped raceway sized to snugly nestthe bearing ball,

said bushings having a combined axial width less than the ball diameterfor axial protrusion thereof,

said bushings further being mounted in the bore with said ball nested inthe raceway, the peripheral outer side of each bushing being fused tothe bore wall along a substantial axial portion to form an integralload-carrying part of the rod end] [4. The device as recited in claim 3,wherein the bore is straight-cylindrically shaped] {5. The device asrecited in claim 3, wherein each of said race surfaces of said bushingsis provided with a liner] [6. The device as recited in claim 3, whereineach of said race surfaces of said bushings is provided with anondeformable, brittle, high temperature-resistant hardened surfacematerial] 7. A metallic method for making a self-aligning sphericalbearing comprising selecting a bearing ball,

forming a mbtallic load-carrying housing having a bore,

forming an annular metallic bushing with a truncated spherically shapedinner raceway and an outer peripheral wall sized to fit within the bore,said inner raceway being sized to snugly nest the ball,

placing the bushing within the bore with the ball nested in the raceway,the peripheral wall of the bushing and the bore wall forming an axiallyextending annular seam.

directing an energized beam generally at the same to melt adjacent sidesthereof to an axial depth extending to a substantial portion of theaxial width of the bushing to weld said bushing to the load-carryinghousing and form an integral part thereof.

8. The method as recited in claim 7, wherein said seam-welding stepfurther comprises directing a focused beam of electrons generally atsaid seam to fuse said adjacent seam walls to a preselected depth.

9. The method as recited in claim 7, wherein said bushing-forming stepfurther includes coating the spherically formed inner surface of thebushing with a brittle, high-temperature-resistant hardened material.

10. A method of making a self-aligning spherical bearing comprisingselecting a truncated bearing ball having a continuous hardened runningsurface,

forming a metallic load-carrying housing of preselected width with abore extending through the width dimension thereof,

forming a pair of like metallic bushings with annular inner surfacesthereof provided with mating halves of a truncated spherically shapedhardened raceway sized to snugly nest the selected ball between theannular raceway portions, with the axial width of the bushings less thanthe diameter of the ball, and the peripheral outer surfaces of thebushings sized to snugly fit within the bore,

placing said bushings within the bore with the ball nested within theannular raceway formed by the mated raceway portions, and with theperipheral outer walls of the bushings forming a seam with the innersurface of the bore, and

directing an energized beam generally at the seam to fuse said bushingsto the bore along a substantial axial length thereof to form an integralload-carrying part of the housing.

I l. The method as recited in claim 10, wherein the bushing, formingstep further includes forming the spherical raceway portion with adiameter slightly less than said ball diameter to provide a slightinterference fit between said ball and said bushings, and

freeing said ball within the spherical raceway with a preselectedtolerance of radial clearance by controlling the width of the fusionzone along said seams.

12. The method as recited in claim 10, wherein the fusion step furthercomprises directing a focused beam of electrons at the seam to fuse thesides thereof to preselected depth.

13. The method as recited in claim 12, wherein said fusion step stillfurther comprises directing the beam of electrons along a first axialdirection at the seam formed by a first of said bushings and the borewall and fusing the peripheral outer wall of the first bushing to asubstantial axial depth, and

directing the beam of electrons along a second axial direction oppositesaid first direction at the seam formed by the second of said bushingsand the bore wall and fusing the peripheral outer wall of the secondbushing to a substantial axial depth.

14. The method as recited in claim 12, wherein said beam of electronsfuses the seams to a depth extending to about percent of the axialwidths of said bushings.

15. The method as recited in claim 9, wherein said bushing-forming stepfurther includes coating said truncated spherically shaped raceways witha liner material.

16. The method as recited in claim 15, wherein said bushing-forming stepfurther includes hardening said raceways by coating thereon anondeformable, brittle, high-temperature-resistant, hardened material.

17. The method as recited in claim 16, wherein said coated material isselected from the group consisting of tungsten carbide, chrome carbideand aluminum oxide.

[18. A bearing assembly according to claim 1, in which the bore and theouter surface of said bushing are both cylindrical and snugly nested,and wherein the axial extent of fusion of said surfaces is less than thefull extent of axial overlap of said surfaces] 19. A self-aligningspherical bearing assembly comprising a metallic load-carrying housinghaving a cylindrical bore, a pair of like metallic bushings having outercylindrical surfaces in closely nested and concentrically supportedrelation in said bore, the inner surfaces of said bushings beingspherically concave and concentric in their nested relation, a truncatedbearing ball having nested self-aligning support in the concave surfacesof said bushings, the axially overlapping nested cylindrical surfacesbeing circumferentially continuously fusion-welded to an axial extentwhich is substantially the full axial extent of overlap inwardly from.the axially outer ends of overlap but which is short of the full axiallyinward extent of said bushings.

20. The bearing assembly of claim 19, in which the axially inward extentof welding is substantially 80 percent of the axial extent of each ofsaid bushings.

21. The bearing assembly of claim 19, in which the radial thickness ofthe welds is greatest at the axially outer limits of cylindrical-surfaceoverlap and reduces as a function of axially inward oflset from saidlimits.

22. A self-aligning spherical bearing assembly comprising a metallicload-carrying housing having a bore which at the axially central regionis a circumferentially continuous cylindrical bore, a pair of likemetallic bushings having concave inner surfaces which define matchedparts of a single spherical surface when the axially inner ends of saidbushings are abutted and aligned, the outer surfaces of said bushings inthe region of said axially inner ends being circumferentiallycontinuously cylindrical to match the cylindrical-bore radius of saidregion and being assembled in concentrically supported axial overlapwith the cylindrical bore at said central region, a truncated bearingball having nested self-aligning support in the concave surfaces of saidbushings, and separate circumferentially continuous fusion welds unitingthe axially overlapped regions of said bushings and bore axially outwardof said central region.

References Cited The following references, cited by the Examiner, are ofrecord in the patented file of this patent or the original patent.

8 FOREIGN PATENTS 11/1956 Italy 308-72 US. Cl. X.R.

